Search results for "silica"

showing 10 items of 1092 documents

Rapid and eco-friendly synthesis of graphene oxide-silica nanohybrids

2014

The increasing interest in Graphene oxide (GO) is due to many issues: the presence of both sp2-conjugated atoms and oxygen-containing functional groups provides a strong hydrophilicity and the possibility to further functionalize it with other molecules (i.e. π-π interactions covalent attachment etc.) [1]. Furthermore since the GO is biocompatible and noncytotoxic many studies have been recently focused on the development of GO-based nanodevices for bioimaging DNA detection drug delivery. Due to their low cytotoxicity and large internal surface area silica nanoparticles have been taken into account as promising material for biolabeling and drug loading/delivery. Particular consideration has recently been demonstrated for GO-silica composites because of the potentialities for electrical applications their chemical inertia and stability toward ions exposure. The possibility to combine the extraordinary properties of GO and silica offers several advantages for the realization of nanoprobes for biological applications and of biosensor [12]. The strategy for the fabrication of GO-nanosilica nanohybrids can be schematized as follows: (i) synthesis of GO by oxidizing graphite powder with the method described by Marcano et al. [3] (ii) Preparation of oxygen-loaded silica nanoparticles by thermal treatments in controlled atmosphere in order to induce high NIR emission at 1272 nm from high purity silica nanoparticles. (iii) preparation of GrO-silica nanohybrid films via rapid solvent casting in water. The nanohybrids were tested by XPS FTIR Raman analysis UV photoluminescence analysis TGA Zeta potential measurements electrical tests AFM and SEM. Several nanohybrids were prepared by combining two different typologies of GO and two different samples of silica.
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Characterization of mesoporous silica and its pseudomorphically transformed derivative by gas and liquid adsorption

2007

Abstract Pseudomorphism is a term introduced by mineralogist to describe phase transformation that does not change the shape of a material. Pseudomorphic process, assisted by surfactants, for mesoporous pre-shaped silica particles allows to narrow the mesopore size distribution, to increase the surface area and the pore volume without changing the initial shape of silica particles. The textural, chemical and mechanical comparisons between commercial silica LiChrospher 60 (Merck) and its pseudomorphic transformation at constant particle size and morphology opens a unique opportunity to understand the effects of such mesoporosity transformation and judge the performance of both types of mater…

Thermogravimetric analysisChemistry02 engineering and technologyGeneral Chemistry[CHIM.MATE]Chemical Sciences/Material chemistryMesoporous silica010402 general chemistry021001 nanoscience & nanotechnologyCondensed Matter Physics01 natural sciences0104 chemical sciencesSilanolchemistry.chemical_compoundAdsorptionChemical engineeringMechanics of MaterialsPhase (matter)Surface modificationOrganic chemistryGeneral Materials ScienceParticle sizemesoporous silica0210 nano-technologyMesoporous materialComputingMilieux_MISCELLANEOUS
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Development and characterization of co-loaded curcumin/triazole-halloysite systems and evaluation of their potential anticancer activity.

2014

Abstract Positively charged halloysite nanotubes functionalized with triazolium salts (f-HNT) were employed as a carrier for curcumin molecules delivery. The synthesis of these f-HNT new materials is described. Their interaction with curcumin was evaluated by means dynamic light scattering (DLS) and UV–vis spectroscopy in comparison with pristine unmodified HNT (p-HNT). The curcumin load into HNT was estimated by thermogravimetric analysis (TGA) measurements, while the morphology was investigated by scanning electron microscopy (SEM) techniques. Release of curcumin from f-HNT, at three different pH values, by means of UV–vis spectroscopy was also studied. Furthermore, different cancer cell …

Thermogravimetric analysisCurcuminCell SurvivalScanning electron microscopeTriazolePharmaceutical ScienceAntineoplastic Agentsengineering.materialHalloysiteSettore MED/13 - EndocrinologiaDrug Incompatibilitychemistry.chemical_compoundhalloysite nanotubes triazolium salts drug carrier curcumin in vitro anticancer activityDynamic light scatteringCell Line TumorHumansTechnology PharmaceuticalOrganic chemistrySolubilityCell ProliferationSettore CHIM/02 - Chimica FisicaDrug CarriersNanotubesSettore CHIM/06 - Chimica OrganicaTriazolesDrug LiberationchemistryThermogravimetryMicroscopy Electron ScanningengineeringCurcuminClayAluminum SilicatesDrug carrierNuclear chemistry
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Tin-based mesoporous silica for the conversion of CO2 into dimethyl carbonate.

2011

Sn-based SBA-15 was prepared by reacting di-n-butyldimethoxystannane with SBA-15 pretreated with trimethylchlorosilane (TMCS) to cap the external hydroxyl groups. Small-angle X-ray diffraction (SXRD), infrared spectroscopy (IR), nitrogen adsorption/desorption, transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and inductively coupled plasma atomic emission (ICP-AES) measurements allow us to propose that the organotin species are located within the pore channels of the mesoporous host. This novel material catalyzes selectively the coupling of CO(2) with methanol to dimethyl carbonate (DMC). The reaction time-conversion dependence shows that a turnover number (TON) of 1…

Thermogravimetric analysisFormatesChemistryGeneral Chemical EngineeringMethanolInorganic chemistryInfrared spectroscopychemistry.chemical_elementMesoporous silicaCarbon DioxideSilicon DioxideCatalysisCatalysischemistry.chemical_compoundGeneral EnergyTinDesorptionEnvironmental ChemistryGeneral Materials ScienceDimethyl carbonateTinMesoporous materialPorosityChemSusChem
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MCM-41 silica effect on gel polymer electrolytes based on thermoplastic polyurethane

2012

Abstract Polymer electrolytes were prepared from thermoplastic polyurethane with addition of mixture of N-ethyl(methylether)-N-methylpyrrolidinium trifluoromethanesulfonimide (PYRA12O1TFSI) ionic liquid, lithium bis(trifluoromethanesulfoneimide) salt and propylene carbonate. MCM-41 mesoporous silica was added in proportions ranging from 5 to 20 wt.% with respect to TPU. The electrolytes were characterized by thermogravimetric analysis, differential scanning calorimetry, linear voltammetry and impedance spectroscopy. The MCM-41 addition to the system was found to improve the electrochemical stability of the membranes and to reduce the gel electrolyte/metallic Li interfacial resistance. The f…

Thermogravimetric analysisMCM-41 mesoporous silicaMaterials scienceGeneral Chemical EngineeringLithium batterieThermoplastic polyurethaneImpedance spectroscopyElectrolyteLithium batteries Thermoplastic polyurethane Ionic liquid MCM-41 mesoporous silica Impedance spectroscopyIonic liquidMesoporous silicaDielectric spectroscopyThermoplastic polyurethanechemistry.chemical_compoundDifferential scanning calorimetryLithium batterieschemistryChemical engineeringIonic liquidPropylene carbonatePolymer chemistryElectrochemistrySettore CHIM/02 - Chimica FisicaElectrochimica Acta
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Pharmaceutical properties of supramolecular assembly of co-loaded cardanol/triazole-halloysite systems

2015

Halloysite nanotubes were explored as drug carrier for cardanol, which is considered as a promising natural anticancer active species. To this aim, besides the pristine nanoclay, a chemical modification of the nanocarrier was performed by attaching triazolium salts with different hydrophobicity at the outer surface of the hollow nanotubes. The interaction between cardanol and nanotubes was highlighted in solution by HPLC. This method proved the loading of the drug into the nanotubes. The solid dried complexes formed by pristine and modified halloysite with the cardanol were characterized by IR spectroscopy, thermogravimetric analysis as well as water contact angle to evidence the structure,…

Thermogravimetric analysisMaterials scienceCell SurvivalPharmaceutical ScienceAntineoplastic Agentsengineering.materialHalloysiteSupramolecular assemblyContact anglePhenolsCell Line TumorOrganic chemistryHumansHEPATOCELLULAR CARCINOMASettore CHIM/02 - Chimica FisicaCardanolHALLOYSITEDrug CarriersHepatocellular carcinoma Cardanol Drug carrier Halloysite HPLCNanotubesChemical modificationSettore CHIM/06 - Chimica OrganicaTriazolesDrug LiberationChemical engineeringengineeringMicroscopy Electron ScanningSettore BIO/14 - FarmacologiaClayAluminum SilicatesNanocarriersHPLCDrug carrierCARDANOLDRUG CARRIER
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Estimation of hydrogen transfer mechanisms in composite materials

2008

Abstract Spill-over effect as a hydrogen transfer mechanism is proposed to explain an increased capacity of hydrogen absorption and improvement of hydrogen activation kinetics in composite material based on the AB5 type metal hydride and powdered glass. A raw lanthanum nickel alloy AB5 with small amount of additives was used as catalyst and bulk material for hydrogen storage, and a borosilicate glass powder with developed surface was applied as a support material. Thermogravimetric technique to determine an absorbed amount of the hydrogen in materials and X-ray powder diffraction analysis for structural investigations was used.

Thermogravimetric analysisMaterials scienceHydrogenHydrideBorosilicate glassComposite numberchemistry.chemical_elementGeneral ChemistryCondensed Matter PhysicsCatalysisHydrogen storagechemistryGeneral Materials ScienceComposite materialPowder diffractionSolid State Ionics
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Silica aerogel–metal composites produced by supercritical adsorption

2010

Abstract Silica aerogel has been loaded with ruthenium acetyl acetonate (Ru(acac) 3 ) by adsorption from supercritical carbon dioxide. Adsorption isotherms and kinetics were measured at different pressures and temperatures. The properties of impregnated aerogel were obtained by optical and electron microscopy (SEM), X-ray microanalysis (EDX) and thermogravimetric analysis (TGA). Results showed that Ru(acac) 3 can be uniformly dispersed into the aerogel up to 5 wt%. Moreover, precursor loading is controllable by properly changing operating conditions. The adsorbed metallorganic compound has been reduced to elemental ruthenium by heat treatment without inducing degradation and morphological c…

Thermogravimetric analysisSupercritical carbon dioxideMaterials scienceMetal-matrix compositesGeneral Chemical EngineeringAerogelschemistry.chemical_elementSilicaAerogelCondensed Matter PhysicsMicroanalysisRutheniumGas adsorptionMetalAdsorptionChemical engineeringchemistryvisual_artvisual_art.visual_art_mediumPhysical and Theoretical ChemistrySupercritical adsorptionCompositesThe Journal of Supercritical Fluids
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Effect of some additives on the reactions in fly ASH-Ca(OH)2system

2004

Differential thermal analysis and thermogravimetry were used to evaluate the effect of some additives, such as CaSO4, CaCl2 and silica fume amorphous silica from ferrosilicon synthesis on the mechanism and kinetics of reactions occurring in fly ash-Ca(OH)2 system. The accelerating role of these additives was demonstrated from the data relating to Ca(OH)2 consumption in hydrated pastes, determined by TG measurements.

ThermogravimetryFerrosiliconMaterials scienceSilica fumeChemical engineeringFly ashDifferential thermal analysisKineticsPozzolanic reactionPhysical and Theoretical ChemistryComposite materialCondensed Matter PhysicsThermal analysisJournal of Thermal Analysis and Calorimetry
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Thermally induced structural modifications and O2 trapping in highly porous silica nanoparticles

2014

Abstract In this work we investigate by Raman spectroscopy the effect of isochronal (2 h) thermal treatments in air in the temperature range 200–1000 °C of amorphous silicon dioxide porous nanoparticles with diameters ranging from 5 up to 15 nm and specific surface 590–690 m2/g. Our results indicate that the amorphous structure changes similarly to other porous systems previously investigated, in fact superficial SiOH groups are removed, Si–O–Si linkages are created and the ring statistic is modified, furthermore these data evidence that the three membered rings do not contribute significantly to the Raman signal detected at about 495 cm−1. In addition, after annealing at 900 and 1000 °C we…

Thin layersMaterials scienceSettore FIS/01 - Fisica SperimentaleAnalytical chemistryNanoparticleAtmospheric temperature rangeCondensed Matter Physicslaw.inventionAmorphous solidNanostructures Amorphous materials Luminescence Raman spectroscopy and scattering Heat treatment Porous silicasymbols.namesakelawsymbolsGeneral Materials ScienceSurface layerElectron paramagnetic resonancePorous mediumRaman spectroscopy
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